This pilot study on the Impact of a Non-commercialism Policy in Seattle Schools will assess and evaluate obesity-related health outcomes of a real-life policy decision, recently voted on and adopted by the Seattle School Board. The policy, developed in response to several years' advocacy by parents and citizen groups, is intended to decrease commercialism in Seattle Public Schools by reducing the students' exposure to advertising and other marketing pressures, including those from commercial food vendors. The timetable and details of policy implementation are left to school principals. For purposes of this pilot study, the Seattle School District has agreed to accelerate the implementation of the policy in one high-school (intervention) and to delay it by a year in another (control). The two schools are matched for size and student characteristics and have 90% minority enrollment. In the first year, the intervention high school will receive funds and staffing to promote an environmental change related to an accelerated adoption of the District policy. The same funds and staffing will be available during the second year to the control school. Our primary research hypothesis is that freeing the school environment from commercial pressures will affect the students' attitudes, intentions, and behaviors related to nutrition and physical activity. The School Health Index, developed by the CDC, will be the main measure of the two schools' environment at baseline and following the intervention. Survey questions of students' attitudes and behaviors will be based on the Teen Health Survey that is administered in Seattle schools. For reasons of privacy and confidentiality, students in Seattle schools are not routinely weighed, and measured BMI data are not available. The students' weights at baseline and at the end of the study will be obtained with the cooperation of the school-based health centers. The study will also document the process of policy development and implementation at each school. The School District is interested in developing monitoring tools that can be used as indicators of progress toward improving the school environment and in identifying barriers to change. Study results will allow Seattle Public Schools to evaluate the health impact of policymaking decisions, preparatory to a larger randomized controlled trial. This collaborative pilot represents a radically different approach to school-based health interventions, many of which are never adopted as a sustainable policy by the district or by individual schools. Helping to implement and evaluate a real-life policy holds greater promise for sustainability and for building coalitions between researchers, public health agencies and public schools .